Acoustic transducers are utilized in a variety of medical applications for transmitting and receiving acoustic signals through the body. In cardiac rhythm management applications, for example, acoustic transducers can be used for telemetrically communicating with and powering implantable medical devices, and for providing therapy to a patient. An example telemetry system employing acoustic transducers is described, for example, in U.S. Pat. No. 7,024,248 to Penner et al., entitled “Systems and Methods For Communicating With Implantable Devices,” which is incorporated herein by reference in its entirety for all purposes. Acoustic transducers are frequently utilized in other medical fields such as medical imaging (e.g., ultrasonography) to permit non-invasive visualization of internal body structures or organs within the body.
In some cases, piezoelectric transducers are used to generate acoustic waves that can be transcutaneously transmitted into or received from the body. Such devices are typically placed in intimate contact with the patient's skin, and utilize the mechanical and electrical properties of piezoelectric materials to enable electrical to acoustic transduction. To facilitate the transmission and receipt of acoustic waves through the skin, an acoustic coupling medium (e.g., an acoustic gel) is sometimes used to reduce or eliminate the presence of air at the interface between the skin and the transducer, which due to its low acoustical impedance, can cause reflection and attenuation losses of the acoustic energy at the interface.
As a result of this property of acoustic interfaces, individuals wearing acoustic devices must often confirm the proper placement of the acoustic transducer on the skin, and in some cases must ensure that an adequate coupling medium is present on the surface of the skin to provide adequate impedance coupling at the transducer/skin interface. For untrained individuals unfamiliar with such devices, or in those cases where the device is to be placed on the skin for extended periods of time, the monitoring of the acoustic coupling may be difficult or even prohibitive. In certain settings such as in an ambulatory setting, for example, the acoustic transducer may become dislodged from the skin, requiring the individual or caregiver to reapply the transducer to reestablish the acoustic transmission.